The present invention relates generally to ergonomic chairs or seats. More particularly, the invention relates to chairs or seats that are configured to provide effective and comfortable back support.
A very large number of articles for sitting are available on the market, many of which purport to provide comfortable and ergonomically effective support for the back. However, such pre-existing chair and seat designs are frequently complicated, expensive, and provide ineffective support of the spine. Furthermore, while many of these seats or chairs can be adjusted to suit a particular individual when seated in a single position, the chairs do not generally provide effective ergonomic support of the spine if the user moves. For example, the spatial relationship between the backrest and the seat of a chair in many pre-existing chair designs will change to a negative or less comfortable relationship with the user""s back when the user leans back in the seat or chair.
What is needed is a seating device such as a chair or seat that is relatively simple and inexpensive to construct, that provides back support that is superior to the support provided by preexisting chair designs, and that will also provide effective support to a users back and spine when the user leans back in the chair.
Accordingly, the present invention comprises a seat or chair configuration that supports the users back at the junction between the lower thoracic vertebrae and the upper lumbar vertebrae and surrounding tissues. Support in this region assists the spine in maintaining a good posture, and also partially supports the weight of the spine above the lumbar region of the spine, which reduces the compressive forces experienced by the lumbar region of the spine. Another aspect of the invention comprises a seat or chair configuration that provides a selected degree of traction applied to the lumbar region of the spine when the user leans back in the seat or chair.
The invention may be incorporated into many other kinds of chairs or other kinds of seating, including but not limited to car seats, sofas, and the like. A preferred embodiment of the chair comprises a seat support structure, a seat operably connected to the support structure, and a backrest that is positionable to provide primary support to the spine in the region between the 1st lumbar vertebrae and the 12th thoracic vertebrae of a user of the chair, and in some embodiments may also support the region between the 11th thoracic vertebrae and the 2nd nd lumbar vertebrae. The force applied by the backrest preferably includes both a vertical component or vector and a horizontal component or vector. The vertical vector partially supports the weight of the user above the lumbar region of the spine preferably reducing the compressive forces experienced by the lumbar region of the spine. In a preferred embodiment, the backrest is configured not to provide support directly to the lumbar region of the spine below the 2nd lumbar vertebrae.
In some embodiments the support structure supporting the seat includes one or more chair legs. In other embodiments, the support structure comprises a base including a mechanism for controlling and adjusting the height of the seat. Some embodiments may include a footrest. The footrest may comprise a body with a triangular cross section and an off center axis extending between the first end and the second ends. In still other embodiments, the backrest includes a protrusion for providing additional support for the thoracic portion of the spine. In further embodiments, the backrest is coupled to a backrest support structure configured to apply a selected amount of traction on a users spine as the backrest is deflected backwards as the user leans back in the chair. The preferred amount of traction is between {fraction (1/16)} inch and xc2xc inch for each xc2xe inch to 1xc2xcinch of backwards deflection, and more preferably xe2x85x9 inch for each 1 inch of backwards deflection of the backrest.
In some embodiments, the backrest support structure comprises a support arm made of a flat sheet of resilient material having a length divided into four regions comprising a lower end section, a lower intermediate section, an upper intermediate section, and an upper end section. The depth of the seat may be adjustable by moving the lower end section of the support arm relative to a coupling affixed to the underside of the seat, and the height of the backrest may be adjustable along a length of an upper end section of the support arm. In alternate embodiments, the support arm may be coupled to the seat support structure, rather than to the underside of the seat.